Critically ill patients are often treated with continuously infused H-2 antagonists to prophylax against stress ulceration. We hypothesize that low-dose continuous intravenous infusion famotidine would be a safe and effective modality for elevating gastric pH above 4.0 in at least 80% of patients. We propose to place a nasogastric tube/pH probe into the stomach of 10 normal volunteers and correlate the pH response and serum famotidine levels during four different infusion rates.